Color liquid crystal display device and method of manufacturing the same, and method of manufacturing a color filter substrate

ABSTRACT

To provide a semi-transmissive type color liquid crystal display device that is capable of realizing high color reproducibility as well as increase in reflection brightness upon light transmission and upon light reflection. In display pixel elements of a color filter substrate used in the semi-transmissive type color liquid crystal display device, a color filter layer formed on a reflection part is thin and a color filter layer formed on a transmission part is thick, and a thickness of a metallic reflective film formed on the reflection part is set to 0.2 μm or more. Further, the color layer filter at the transmission part and the color layer filter at the reflection part are formed at the same time, and a continuous color filter layer is obtained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a color liquid crystal display deviceused in a portable information device such as a mobile phone or anelectronic notebook, a personal computer, or the like. In particular,the invention relates to a semi-transmissive type color liquid crystaldisplay device serving both as a reflection type color liquid crystaldisplay device and a transmission type color liquid crystal displaydevice, a method of manufacturing the same, and a method ofmanufacturing a color filter substrate.

2. Description of the Related Art

As a color liquid crystal display device used for a display device in amobile phone, a portable information device, or the like, three types: atransmission type, a reflection type, and a semi-transmissive type ofcolor liquid crystal display devices are used. Hereinafter, briefdescription will be made of the three types of conventional color liquidcrystal display devices with reference to the accompanying drawings.FIG. 1 is a sectional view of a conventional transmission type colorliquid crystal display device. A light shielding film 4 and colorfilters 3 are formed on the surface of a lower transparent substrate 1A.The color filter 3 includes colored portions of three primary lightcolors: red (R), green (G), and blue (B) according to a pattern. Thatis, the colored portions of red, green, and blue are formed in the colorfilter 3 in an arbitrary pattern such as a stripe or a mosaic. The lightshielding film 4 is provided between the colored portions asappropriate. A transparent flattening film 5 is provided on the surfacesof the light shielding film 4 and the color filters 3, and on top of theflattening film a transparent electrode 2A is formed in an arbitrarypattern. In the case of a passive type color liquid crystal displaydevice, the transparent electrode 2A is formed in such a pattern thatthe transparent electrode crosses colored layers 3R, 3G, and 3B of thecolor filters. That is, the transparent electrode 2A is formed as acommon line. In the case of an active type color liquid crystal displaydevice, the transparent electrode 2A is not patterned, and may be leftas it is in an electrode shape after performing film formation by usinga film formation mask. Those layers are collectively referred to as acolor filter substrate 6.

As shown in the drawing, a gap between the color filter substrate 6 anda transparent substrate 1B as a counter substrate is uniformlymaintained by sealing members 7 and spacers 9, and a liquid crystal 10is filled in a space defined by the color filter substrate 6 and thetransparent substrate 1B. A display panel thus structured is sandwichedbetween a pair of deflection plates 12 and 13. In addition, orientationfilms (not shown) are provided on the surfaces of transparent electrodes(2A and 2B) (see Tatsuo Uchida (Nov. 1, 1994) “New Technology of LiquidCrystal Display”, p.167-174, published by Kogyochosakai Publishing Co.,Ltd., for instance).

FIG. 2 is a sectional view of a conventional reflection type colorliquid crystal display device. The aforementioned description of thetransmission type color liquid crystal display device of FIG. 1 will beomitted. As shown in FIG. 2, a metallic reflective film 11 forreflecting outside light is provided between the transparent substrate1A and the color filters 3. Therefore, the deflection plate 12 becomesunnecessary unlike the transmission type display device shown in FIG. 1.In this case, the deflection plate 13 is often provided with aquarter-wave plate for returning phase-shifted light due to reflectionat the metallic reflective film 11 and a layer having a scatteringfunction for glare prevention of regularly reflected light at themetallic reflective film 11 (see Tatsuo Uchida (Nov. 1, 1994) “NewTechnology of Liquid Crystal Display”, p. 167-174, published byKogyochosakai Publishing Co., Ltd., for instance).

FIG. 3 is a sectional view of a conventional semi-transmissive typecolor liquid crystal display device. The above-mentioned descriptionregarding the color liquid crystal display devices will be omitted. Asshown in FIG. 3, the metallic reflective film 11 formed between thetransparent substrate 1A and color filters 3 is partially removed.Therefore, both functions of a reflection part and a transmission partare achieved in one pixel element. Further, the deflection plate 12 isprovided on the outer side surface of the transparent substrate 1A (seeJP 11-52366 A (pages 2-4, FIG. 1), for instance).

Subsequently, brief description will be made of a method ofmanufacturing the conventional semi-transmissive type color liquidcrystal display device. First of all, as shown in FIG. 4A, the metallicreflective film 11 is formed on the surface of the transparent substrate1A by a vacuum film formation method such as sputtering or a vacuumdeposition method so as to have the thickness at a level in which nolight is transmitted therethrough. To obtain sufficient light shieldingproperty, the thickness of the metallic reflective film 11 needs to be0.10 μm or more. In the case where the metallic reflective film 11 ismade of aluminum or an aluminum alloy, the thickness thereof is set toapproximately 0.125 μm in general. In the case where the metallicreflective film 11 is made of silver or a silver alloy, the thicknessthereof is generally set to about 0.10 μm. Next, as shown in FIG. 4B,the metallic reflective film 11 is patterned by a photolithographymethod. Patterning is conducted such that the reflection part and thetransmission part are established in each pixel element in a displayscreen of the display panel. In FIG. 4B, a part where the metallicreflective film 11 is left corresponds to the reflection part, and apart where the metallic reflective film 11 is removed becomes thetransmission part. The proportion of the reflection part and thetransmission part can be set arbitrarily through patterning.

Then, as shown in FIG. 4C, the patterned light shielding film 4 isformed. To obtain the light shielding film 4, the entire surface of thetransparent substrate 1A is applied with a liquid photoresist containingblack pigments, and thereafter the resist is patterned into a desiredshape by the photolithography method. Typically, this is called a blackmatrix as being formed in a matrix. In these days, to increase thereflection light amount of the color liquid crystal display device, thelight shielding film 4 is formed into a stripe shape (black stripe), orsometimes the light shielding film 4 is provided only in a frame partaround the color liquid crystal display device and not provided in itsdisplay area.

Subsequently, as shown in FIG. 4D, the colored portions 3R constitutingthe color filters are formed. To obtain red color filters, the entiresurface of the transparent substrate 1A is applied with a liquidphotoresist containing red pigments, and the resist is then patternedinto a desired shape by the photolithography method. The coloredportions are usually formed in a stripe shape along the matrix of thelight shielding film 4. In a similar manner, the colored layers 3G(green) and 3B (blue) are sequentially formed to obtain such a shape asshown in FIG. 4E. Here, there is almost no difference between thethickness of the respective colored layers 3R, 3G, and 3B obtainedthrough the application of the liquid color resist on the metallicreflective film 11 (that is, at the reflection part) and the thicknessof the respective colored layers 3R, 3G, and 3B on the transparentsubstrate 1A where the metallic reflective film 11 is removed (that is,at the transmission part). This is because the metallic reflective film11 is a thin film having the thickness of approximately 0.10 μm, and theliquid photoresist is turned into a film along the surface shape of thesubstrate 1A.

Next, as shown in FIG. 4F, the flattening film 5 made of a transparentresin is formed on the surfaces of the color filters 3 in which thosecolored portions are formed. In general, the flattening films is formedthrough application of a liquid material by use of a spinner. As shownin FIG. 4G, the transparent electrode 2A is sequentially formed on thesurface of the flattening film 5. The flattening film 5 has adhesivenesswith respect to the transparent electrode 2A, resistance to patterning,and the like. The transparent electrode 2A is typically formed by asputtering method so as to have desired thickness and resistance valuecharacteristics. In general, a conductive material containing anincompletely oxidized alloy of indium (In) and tin (Sn) is used forforming the transparent electrode 2A.

In this way, the substantially planer color filter substrate 6 shown inFIG. 4H is completed. As described above, by using the color filtersubstrate 6, the conventional semi-transmissive type color liquidcrystal display device is formed. Hereinafter, brief description will bemade of a method of manufacturing a liquid crystal display device.Orientation films provided on the surfaces of the color filter substrate6 and a counter substrate 8 are commonly formed by an offset printingmethod. The spacers 9 provided between the color filter substrate 6 andthe counter substrate 8 are uniformly distributed by a dispersionmethod. The sealing members 7 are formed by a screen printing method inusual cases. The color filter substrate 6 and the counter substrate 8are glued together, and after that the liquid crystal 10 is filled inthe space corresponding to the gap between the color filter substrate 6and the counter substrate 8.

Further, recently, there has come along a technique for improving colorreproducibility at the time of light transmission by increasing thethickness of the color filter at the transmission part as compared tothe thickness of the color filter at the reflection part (see JP2002-303861 A (pages 2-4, FIG. 1), for instance). Brief description willbe made of the technique by referring to FIGS. 5A to 5G and 6. First, asshown in FIG. 5A, the surface of the transparent substrate 1A is appliedwith a photosensitive transparent resin, and resin layers 14 are formedby the photolithography method. To obtain the resin layers 14, aconsiderably complicated method is adopted as follows. That is, apositive type photoresist having a property of melt flow uponpost-baking is formed in a desired pattern, and then projections anddepressions are formed on the layer surface by post-baking. After that,application of the positive type photoresist is conducted again to coverthe projections and depressions. Thus, the photolithography method isused twice by way of double photoresist applications (see JP 6-11711 A(pages 2 and 3, FIG. 4), for instance) . As in the pattern of themetallic reflective film 11 described in the case of the above-mentionedconventional semi-transmissive type color liquid crystal display device,the resin layers 14 have a shape in which the reflection part and thetransmission part are established in one pixel element. Next, themetallic reflective film 11 is formed on the entire surface of thetransparent substrate 1A by sputtering or the like, and then the film ispatterned by the photolithography method to have such a pattern that themetallic reflective film 11 overlaps the surfaces of the resin layers14. After that, as shown in FIG. 5C, the light shielding film 4 isformed. To obtain the colored portions of the color filters, red coloredportions 3R and 3R2, green colored portions. 3G and 3G2, and bluecolored portions 3B and 3B2 are formed by employing the photolithographymethod six times with negative type color resists for the reflectionpart and the transmission part, separately (FIGS. 5D to 5F). Asdescribed above, by using the color filter substrate 6, anotherconventional semi-transmissive transmissive type color liquid crystaldisplay device shown in FIG. 6 is obtained.

As another method of forming a color filter, there is also disclosed inJP 2002-303861 A (pages 2-4, FIG. 1) a method of forming color filtersat the reflection part and the transmission part at the same time.However, no description is given of a specific method of doubling thethickness of the color filter at the transmission part as compared tothe thickness of the color filter at the reflection part, and it ismerely described that “application is performed so as to have thethickness” in the transmission area twice as large as the thickness inthe reflection area. The inventors of the present invention canunderstand that the thickness at the reflection part and that on thetransmission part are changed in employing the photolithography methodsix times as described above, but conceive that it is not easy tounderstand the method of “forming color filters at the reflection partand the transmission part at the same time”, which offers no specificdescription.

As described above while referring to FIGS. 5A to 5G and 6, in order toachieve a satisfactory color balance upon light reflection andtransmission, the semi-transmissive type color liquid crystal displaydevice having the thickness at the transmission part larger than thethickness at the reflection part has been devised. However, such asemi-transmissive type color liquid crystal display device has thefollowing problem. That is, since the colored portions of the respectivecolors in the color filters are formed by performing a photolithographystep one time each, the color filters 3 having substantially the samethickness are formed in any of the display areas. Accordingly, levels ofcolor density and brightness achieved by the respective color filtersare the same in the entirety of the display area. In addition, from therelationship regarding productivity of the reflective film 11, thethickness thereof is set to about 0.10 μm, and the colored portions areformed on the reflective film 11 through a spinner method by using theliquid color resist, so that there is almost no difference in filmthickness at the reflection part and the transmission part. Therefore,there is also almost no difference in color density and brightnessachieved by the color filters at the entirety of the display area. Inother words, if the film thickness of the color filter is increased toenhance display color density of the semi-transmissive type color liquidcrystal display device, transmittance of the color filter is lowered,which leads to a problem of decrease in brightness at the transmissionpart and the reflection part. Conversely, if the film thickness of thecolor filter is decreased with the emphasis on brightness at the displayimage, there is a problem in that the display color density cannotsufficiently be obtained. Moreover, at the reflection part, outsidelight is transmitted through the color filter layer and thereafterreflected at the metallic reflective film, and the reflected lightreturns while being transmitted through the color filter layer again.Thus, the incident light amount is drastically reduced because of thelight transmission through the color filter layer twice. For thisreason, there is a problem in that visibility of the color liquidcrystal display device deteriorates.

Further, in addition to this structure, it is conceivable to provide astructure in which after forming color filters having small thickness,color filters are further formed only at the transmission part 12.However, in this structure, the number of times to perform thephotolithography step for the color filters needs to be doubled, i.e.,six times, resulting in lowering productivity and increasing industrialand economic burdens such as increase in the number of defects. In thecase of the color filters used for the color liquid crystal displaydevice having a refined color filter shape, since high-precisionalignment by the above-mentioned photolithography method is required, itis necessary to perform an extremely troublesome manufacturing step. Atthe same time, productivity severely deteriorates and also yield islowered so that industrial and economic problems are unavoidable.

Note that, the inventors of the present invention point out that theextremely troublesome method of forming the resin layers 14 is aprerequisite also for the method of setting the thickness of the colorfilter at the transmission part larger than that of the color filter atthe reflection part through the simultaneous formation of the colorfilters, which is disclosed in JP 2002-303861 A (pages 2-4, FIG. 1).

SUMMARY OF THE INVENTION

The present invention has been made with a focus on the above-mentionedproblems inherent in the semi-transmissive type color liquid crystaldisplay device described above. An object of the present invention is toprovide a color liquid crystal display device that is capable ofrealizing high color reproducibility as well as increase in reflectionbrightness upon light transmission and upon light reflection. Anotherobject of the present invention is to provide a method of manufacturingthe color liquid crystal display device. In addition, still anotherobject of the present invention is to provide a method of manufacturinga color filter substrate.

According to the present invention, there is provided a color liquidcrystal display device, in which, in display pixel elements, a thicknessof a color filter layer provided on a reflection part is small and athickness of the color filter layer provided on a transmission part islarge, and a thickness of a metallic reflective film formed on thereflection part is set to 0.2 μm or more. Also, in the color liquidcrystal display device according to the present invention, the metallicreflective film is provided in a part of an area of the display pixelelement to establish a reflection part and a transmission part in thedisplay pixel element; colored layers are integrally provided on themetallic reflective film and at the transmission part where the metallicreflective film is not provided in the display pixel element; and a sumof a thickness of the metallic reflective film and a thickness of thecolored layer on the metallic reflective film is larger than a thicknessof the colored layer at the transmission part. Further, the sum of thethickness of the metallic reflective film and the thickness of thecolored layer on the metallic reflective film is larger than thethickness of the colored layer at the transmission part by 0.15 μm to0.30 μm.

Also, a color liquid crystal display device according to the presentinvention, includes: a color filter substrate having a metallicreflective film, colored layers, and a transparent electrode formed on atransparent substrate; a counter substrate having an opposite electrodethat is opposite to the transparent electrode and constitutes a displaypixel element with the transparent electrode; and a liquid crystal layerformed between the color filter substrate and the counter substrate, inwhich the metallic reflective film having a thickness of 0.2 μm or moreis formed on a part of an area of the display pixel element; and thecolored layers are integrally formed on the metallic reflective film andat an area where the metallic reflective film is not formed in thedisplay pixel element.

Further, a light shielding film is provided between the colored layers.The light shielding film is provided on the metallic reflective film oron an area of the transparent substrate where the metallic reflectivefilm is not formed.

Also, a method of manufacturing a color liquid crystal display deviceaccording to the present invention, includes: establishing a reflectionpart and a transmission part by forming a metallic reflective filmhaving a thickness of 0.2 μm or more on a part of an area of atransparent substrate where the display pixel element is to beconstituted; forming colored layers at the reflection part and thetransmission part at the same time; forming a color filter substrate byrepeatedly performing the colored layer formation for each color;forming the transparent electrode having a predetermined pattern on thecolor filter substrate; forming the opposite electrode having apredetermined pattern on the counter substrate; arranging the colorfilter substrate and the counter substrate such that the transparentelectrode and the opposite electrode are opposed to each other; andforming the liquid crystal layer in a space between the transparentelectrode and the opposite electrode.

Further, the method of manufacturing a color liquid crystal displaydevice further includes: forming a light shielding film on a part of themetallic reflective film before the colored layer formation.Alternatively the method further includes: forming a light shieldingfilm on a part of an area of the transparent substrate where themetallic reflective film is not formed before the colored layerformation. Also, during the colored layer formation, each of the coloredlayers is formed by supplying a liquid color resist in a predeterminedarea surrounded by the light shielding film. Further, after the supplyof the liquid color resist, the resist is left to stand in a liquidstate for 1 minute or longer before being dried.

Further, a thickness of the metallic reflective film is in a range from0.4 μm to 0.6 μm. Also, a thickness of colored layers at the reflectionpart is in a range from 0.4 μm to 0.8 μm.

A method of manufacturing a color filter substrate according to thepresent invention, includes: establishing a reflection part and atransmission part by forming a metallic reflective film having athickness of 0.2 μm or more on a part of a transparent substrate;forming colored layers at the reflection part and the transmission partat the same time; and forming a color filter by repeatedlyperforming-the colored layer formation for each color. Further, duringthe colored layer formation, the colored layer on the metallicreflective film is formed to have a thickness in a range from 0.4 μm to0.9 μm, and at the same time the colored layer at the transmission partis formed to have a thickness in a range from 0.55 μm to 1.0 μm.

As described above, by setting the thickness of the color filter at thereflection part different from that of the color filter at thetransmission part, without any additional manufacturing step, it ispossible to realize the color reproducibility upon light transmission ata competitive level with the color reproducibility upon light reflectionas well as the increase in brightness upon light reflection. Inaddition, no manufacturing step is newly added, whereby industrial andeconomic losses such as yield deterioration are suppressed, and themethod of manufacturing the high-quality and high-productivity butinexpensive semi-transmissive type color liquid crystal display devicecan be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a sectional view schematically showing a structure of aconventional transmission type color liquid crystal display device;

FIG. 2 is a sectional view of a conventional reflection type colorliquid crystal display device;

FIG. 3 is a sectional view of a conventional semi-transmissive typecolor liquid crystal display device;

FIGS. 4A to 4H show a method of manufacturing a conventionalsemi-transmissive type color liquid crystal display device;

FIGS. 5A to 5G show a method of manufacturing another conventionalsemi-transmissive type color liquid crystal display device;

FIG. 6 is a sectional view of another conventional semi-transmissivetype color liquid crystal display device;

FIG. 7 is an enlarged view of a part of a semi-transmissive type colorliquid crystal display device according to an embodiment of the presentinvention;

FIG. 8 is an enlarged view of a part of a semi-transmissive type colorfilter substrate of the present invention;

FIG. 9 is a sectional view of the semi-transmissive type color liquidcrystal display device according to the embodiment of the presentinvention; and

FIGS. 10A to 10F show a method of manufacturing a semi-transmissive typecolor liquid crystal display device according to an embodiment of thepresent invention.

DETAITLED DESCRIPTION OF THE PREFERRFD EMBODIMENTS Embodiment

Hereinafter, description will be made of a semi-transmissive type colorliquid crystal display device according to an embodiment of the presentinvention with reference to the drawings. FIG. 7 is an enlarged planview showing a part of a pixel of a semi-transmissive type color liquidcrystal display element. The figure shows that one pixel is composed ofthree pixel elements respectively having colored portions (R, G, and B)that constitute color filters. In addition, a light shielding film 4 isprovided between each of the pixel elements. FIG. 8 schematically showsa cross sectional structure of a color filter substrate corresponding toa cross section taken along a line A-A in FIG. 7, that is, a crosssection of the pixel element having red colored portions. As shown inthe drawing, a metallic reflective film 11 and red colored layers 3R areprovided on the surface of a transparent substrate 1A. In the pixelelement, one colored layer 3R exists at a part as being provided on themetallic reflective film (reflection part) while the other colored layer3R is present at another part as being provided on the transparentsubstrate without involving the metallic reflective film (transmissionpart). More specifically, a portion where an opening is provided in themetallic reflective film corresponds to the transmission part. In thisembodiment, the colored layer at the transmission part and the coloredlayer at the reflection part are formed of a continuous layer. Inaddition, the light shielding film 4 is provided on a part on themetallic reflective film 11. The light shielding film 4 is formed in amatrix so as to surround display pixel elements. In order to improve theappearance of the display screen, the light shielding film 4 is formedalso in an outer periphery of the entire display screen area, which isso-called a frame. On the surfaces of those films, a transparent resinlayer is formed for flattening (hereinafter, referred to as transparentflattening film). Furthermore, a transparent conductive film 2A formedin a desired pattern by a photolithography method is provided on thistransparent flattening film 5.

In usual cases, the thickness of the metallic reflective film 11provided with openings in some areas so as to have a transmittingfunction is set to about 0.12 μm to 0.15 μm. This also corresponds tothe thickness necessary for completely blocking light while eliminatinga cause such as a pinhole that allows light to transmit in the metallicreflective film formed by a vacuum film formation method such assputtering.. In the present invention, the thickness of the metallicreflective film 11 is set to 0.2 μm or more and 1.0 μm or less. Thelarger the thickness of the metallic reflective film 11, the larger thefilm thickness of the colored layer at the transmission part. That is,the difference in film thickness of the colored layers at thetransmission part and the reflection part can be increased. It isconceivable that this is because when a liquid color resist is appliedfor forming the colored layer, an effect for flattening surfaceprojections and depressions is developed owing to the liquid state, inwhich the liquid color resist flows into opening areas (transmissionparts) provided in the metallic reflective film. However, the completelyflat state of the colored layers at the reflection part and thetransmission part may not be achieved in some cases. The thickness atthe transmission part (the thickness of the colored layer) is smallerthan the thickness at the reflection part (the total thickness of themetallic reflective film and the colored layer) . At this time, it isdesirable to set appropriately the total thickness of the metallicreflective film and the colored layer such that this thicknessdifference falls in a range from approximately 0.15 μm to 0.30 μm. Thelarger the thickness at the reflection part (the total thickness of themetallic reflective film and the colored layer), the larger thethickness at the transmission part (the thickness of the colored layer).However, the increase in thickness at the transmission part is not asmuch as the increase in thickness at the reflection part. Consequently,the larger the thickness at the reflection part, the larger the leveldifference between the reflection part and the transmission part. Thethickness at the reflection part is the total thickness of the metallicreflective film and the colored layer so that the total thickness can beadjusted by appropriately selecting the thickness of the metallicreflective film and the thickness of the colored layer individually.

Further, when the thickness of the metallic reflective film is larger,peeling or the like tends to occur due to increase in its internalstress, and therefore there is a possibility of lowering reliability.Thus, the thickness of the metallic reflective film is preferably 0.6 μmor less. On the other hand, to obtain optimal color density andbrightness at the transmission part and the reflection part, a certainlevel of film thickness difference of colored layers is required, sothat the metallic reflective film needs to have thickness to some extentas well. In view of the above, the thickness of the metallic reflectivefilm is preferably in a range from 0.4 μm to 0.6 μm.

In addition, the film thickness of the colored layer provided on themetallic reflective film needs to be 0.4 μm or more to securechromaticity and reproducibility at the time of reflection observation.On the other hand, in order that the thickness of the colored layer atthe transmission part be set to 1.0 μm or less to secure brightness atthe time of observation, after giving consideration to theabove-mentioned level difference, it is preferred to set the totalthickness to be in a range from 0.8 μm to 1.3 μm. Accordingly, thethickness of the colored layer at the reflection part (the colored layeron the metallic reflective film) is preferably in a range from 0.4 μm to0.9 μm.

For example, in the case where the metallic reflective film had thethickness of 0.4 μm, and the thickness of the colored layer at thereflection part was in a range from 0.4 μm to 0.8 μm, that is, the totalthickness at the reflection part was in a range from 0.8 μm to 1.2 μm,the thickness at the transmission part was in a range from 0.55 μm to0.90 μm. Meanwhile, in the case where the metallic reflective film hadthe thickness of 0.4 μm, and the thickness of the colored layer at thereflection part was 0.4 μm, that is, the total thickness at.thereflection part was 0.8 μm, the thickness at the transmission part wasin a range from 0.55 μm to 0.65 μm.

Factors that enhance the above-mentioned flattening function of theliquid color resist include: the viscosity of a color resist; theretention time of the color resist in a liquid state from theapplication thereof on the transparent substrate 1A until being dried;the boiling point of an organic solvent used for the color. resist; andthe like. Although the viscosity of a commonly used color resist is in arange approximately from 5 cp to 15 cp, a resist with a low viscosity ispreferably used in view of enhancing the flattening function. An organicsolvent generally used for a color resist is a mixed solvent containingpropylene glycol monomethyl ether acetate (PGMEA) as its main ingredientand having the boiling point of about 140° C. The higher the boilingpoint, the more the flattening function enhances. In addition, thelonger the time from the color resist application until pre-baking isperformed, that is, a period of time for leaving the color resist tostand in a liquid state after the application, the more likely the colorresist is to be flattened, which is preferable. The optimal time periodmay be varied depending on the viscosity of the color resist and theboiling point of the organic solvent used for the color resist, but theretention time of 1 minute or longer is necessary to flatten the colorresist. There is however no point in leaving the color resist to standuntil the organic solvent evaporates, so that the retention time ispreferably from about 3 minutes to 10 minutes. Those factorsrespectively have correlations as well as restrictions, and thusconsiderations should be given in terms of quality and economicalefficiency such as uniformity in film thickness of the color filters,workability, and productivity.

The present invention will be described further in detail by way of thefollowing examples.

EXAMPLE 1

FIG. 9 shows a schematic sectional view of a semi-transmissive typecolor liquid crystal display device of this example. The metallicreflective film 11, which is provided with openings (transmission parts)in some parts, has the thickness of 0.5 μm, and is made of an aluminumalloy, is provided on the surface of the transparent substrate 1A. Onthe surfaces of the metallic reflective film 11 and its openings, thecolored layers 3R, 3G, and 3B of the primary colors of red, green, andblue are formed. In this example, the film thickness of the coloredlayer at the reflection part is 0.6 μm and the film thickness of thecolored layer at the transmission part is 0.9 μm. Therefore, the totalthickness at the reflection part is 1.1 μm, which is the total thicknessof the 0.5 μm-thick metallic reflective film 11 and the 0.6 μm-thickcolored layer. On the other hand, the total thickness at thetransmission part simply equals to the film thickness of the coloredlayer, which is 0.9 μm. Accordingly, the level difference between thereflection part and the transmission part is 0.2 μm. The leveldifference is formed in the same manner in all the colored layers 3R,3G, and 3B. In a periphery of the display pixel elements of the coloredlayers 3R, 3G, and 3B, the light shielding film 4 having the thicknessof 0.6 μm is formed in a matrix on the surface of metallic reflectivefilm 11. On the surfaces of the colored layers 3R, 3G, and 3B and thelight shielding film 4, the transparent flattening film 5 with thethickness of 2.5 μm is provided. With the transparent flattening film 5,the level difference of 0.2 μm regarding the color layers between thereflection part and the transmission part is eliminated. Thus, the flatsurface (surface irregularity: ±0.03 μm or below) is obtained. Thepatterned transparent electrode 2A is provided on the surface of thetransparent flattening film 5. In this way, the color filter substrate 6is formed.

On the other hand, the counter substrate 8 provided with transparentelectrodes 2B is so arranged as to oppose the color filter substrate 6.The sealing members 7 and the spacers 9 are provided between the colorfilter substrate 6 and the counter substrate 8, thus controlling thethickness of the liquid crystal layer. Although not shown in thedrawing, orientation films are provided to the inner side surfaces ofthe color filter substrate 6 and the counter substrate 8. On the outerside surfaces of the color filter substrate 6 and the counter substrate8, deflection plates 12 and 13 are provided, respectively. Thedeflection plate 12 is combined with a quarter-wave plate, and thedeflection plate 13 is combined with a quarter-wave plate and a lightdiffusion film.

With regard to the thus structured semi-transmissive type color liquidcrystal display device and the conventional semi-transmissive type colorliquid crystal display device, Table 1 shows data comparison about colorreproducibility and reflection brightness. For the conventionalsemi-transmissive type color liquid crystal display device, two displaydevices were prepared in which the metallic reflective film 11 had thethickness of 0.1 μm, and the film thickness of the color filters at boththe reflection part and the transmission part was 0.6 μm (ConventionalExample 1) and 0.9 μm (Conventional Example 2), respectively. That is tosay, such display devices were used that the reflection part and thetransmission part had the same color filter thickness, and the surfaceof the color filter substrate was flat. In addition, the conventionaldisplay devices had the same structure as that of Example 1 except forthe metallic reflective film 11 and the color filter thickness. Thecolor resists for red, green, and blue to be used were identical, whichshowed 30% color density NTSC ratio when having the thickness of 0.9 μm.Evaluation was performed by using the same backlight light source upontransmission and the same white color light source upon reflection, witha spectrophotometer (Minolta CS-1000) for measurement.

[Table 1] Comparison in color reproducibility and reflection brightnessbetween semi-transmissive color liquid crystal display device of thepresent invention and conventional semi-transmissive color liquidcrystal display device (1) Conventional Conventional Example 1 Example 1Example 2 CF Transmission 30% 20% 30% substrate NTSC ratio Reflection40% 45% 56% NTSC ratio Reflection 40% 40% 28% brightness DisplayTransmission 25% 16% 25% device NTSC ratio Reflection 24% 26% 42% NTSCratio Reflection 25% 25% 17% brightness

As shown in Table 1, in Example 1, the color reproducibility at the timeof transmission in the display device was 25% in NTSC ratio, which wasas high as Conventional Example 2, and also the color reproducibility atthe time of reflection was 24% in NTSC ratio and the reflectionbrightness was 25%, which were as high as Conventional Example 1. Thatis, the color reproducibility at the time of transmission and the colorreproducibility at the time of reflection were high and well balanced,and the reflection brightness was high as well.

Now, description will be made of a method of manufacturing asemi-transmissive type color liquid crystal device according to anembodiment of the present invention with reference to FIGS. 10A to 10F.FIG. 10A shows a state in which the metallic reflective film 11 made ofan aluminum alloy is formed on the surface of the transparent substrate1A by sputtering. The film thickness can be adjusted based on timeduration for forming the film. In an inline type sputtering device ofrecent years, plural aluminum alloy material targets can be loaded.Therefore, even when the metallic reflection film used in the presentinvention has the thickness of about 0.5 μm, which is larger than the0.1 μm-thick metallic reflection film used in the conventionalsemi-transmissive type color liquid crystal device, no large differenceoccurs in time period for forming the film. Thus, the reproducibilityhardly changes.

Subsequently, the aluminum alloy reflective film 11 is partially removedin the display pixel element by a photolithography method and etching asshown in FIG. 8 to obtain such a structure as shown in Fig. 10B. Theproportion and shape of removing the metallic reflective film 11 can beset arbitrarily. When the removing area is large, the area of thetransmission part is increased, resulting in high display brightnessupon transmission. In contrast, when the area to be removed is small,high display brightness upon reflection can be obtained. A metal usedfor the reflective film 11 may be aluminum alone having highreflectance, but in general, an aluminum alloy composed of about 5% ofneodymium and about 95% of aluminum is used. The neodymium is mixed forenhancing chemical resistance without decreasing the reflectance. Eachof the mix rates is represented in atomic concentration.

Following this, as shown in FIG. 10C, the light shielding film 4 wasformed in a desired pattern on the surface of the metallic reflectivefilm 11. The light shielding film 4 is prepared by dispersing and mixingfine carbon particles or titanium black in a transparent photosensitiveresin, with the film thickness of 0.6 μm. After application of thetransparent photosensitive resin by a spinner, patterning was performedby the photolithography method to form the light shielding film 4. Sincethe light shielding film 4 is provided on the 0.5 μm-thick metallicreflective film 11 that allows no light to transmit therethrough, evenwhen the light shielding film 4 is as thin as 0.6 μm, there arises noproblem regarding the light blocking property at all. Alternatively,after removing the metallic reflective film 11 under the light shieldingfilm 4, a light shielding film having the film thickness of 1A μm may beprovided on the substrate.

As shown in FIG. 10D, the red colored layers 3R are then formed on thepixel element. For the formation, a liquid red color resist adjusted tohave the viscosity of 8 cp and composed of an organic solvent containingPGMEA as its main ingredient and having the boiling point of about 140°C., was applied by the spinner such that its film thickness on themetallic reflective film 11 became 0.6 μm. In order to sufficientlyeffect the flattening function of the liquid color resist, elapse of 5minutes is waited before performing provisional drying, and thenpatterning was conducted by the photolithography method. At this time,the film thickness of the red colored layers 3R in the transmission partwas 0.9 μm. In a similar manner, each of a liquid green color resist anda liquid blue color resist adjusted to have the viscosity of 8 cp andcomposed of an organic solvent containing PGMEA as its main ingredientwas applied by the spinner such that its film thickness of the coloredlayer at the reflection part (on the metallic reflective film 11) became0.6 μm. In this way, the colored layers 3G and 3B shown in FIG. 10E wereformed, and the film thickness at the transmission part of therespective colors was 0.9 μm.

After that, the transparent flattening film 5 made of a thermosettingpolymer resin is applied by the spinner to have the thickness of 2.5 μm,before being thermally set at 230° C. for 1 hour. On the surface of thetransparent flattening film 5, the transparent conductive film wasformed by sputtering to then form a transparent electrode 2A in adesired pattern by the photolithography method and the etching method.As a result, the color filter substrate shown in FIG. 10F is obtained.By combining the thus manufactured color filter substrate 6 and thecounter substrate 8 with each other, the semi-transmissive type colorliquid crystal display device of the present invention shown in FIG. 9was obtained.

Here, the case where the transmission part was formed at the center ofthe display pixel element is described as an example. However, thereflection part (metallic reflective film) may be formed at the centerof the display pixel element. In such a case, the light shielding filmis provided in a part where the reflective film is not formed on thetransparent surface (that is, the transmission part). Moreover, thenumber of the transmission part in one pixel element is not necessarilylimited to one, and plural transmission parts each having a small areamay be provided in one pixel element. In the case where the reflectivefilm is provided, in FIGS. 7 to 9, the light shielding film is providedso as to surround one pixel element, but the light shielding film maynot be provided in a part of the surrounding area. In FIG. 8, the lightshielding film in a lateral direction is not provided but only the lightshielding film in a vertical direction may be provided to form a stripeshaped color filter.

EXAMPLE 2

Next, Example 2 is described while referring to FIGS. 9 and 10A to 10F,similarly to Example 1. The fundamental structure is the same as that ofExample 1, so that the manufacturing method is mainly described and theabove-mentioned description will be omitted.

In Example 2, a silver alloy material was used for the metallicreflective film 11. The material is an alloy containing silver as itsmain ingredient and composed of about 3% of neodymium, about 1% ofcopper, and about 96% of silver. The neodymium and the copper are mixedfor enhancing chemical resistance without decreasing the reflectance ofsilver. Each of the mixing ratios is represented in atomicconcentration. As in Example 1, the silver alloy is formed into a filmhaving the thickness of 0.4 μm by using the inline type sputteringdevice. After that, the metallic reflective film 11 is formed in adesired pattern by the photolithography method and the etching method(FIG. 10B). Then, the 0.5 μm-thick light shielding film 4 was formed ina desired pattern on the surface of the metallic reflective film 11(FIG. 10C).

A color resist for each of red, green, and blue adjusted to have theviscosity of 10 cp and composed of an organic solvent, which showed 40%color density NTSC ratio when having the thickness of 0.8 μm, containingliquid carbitol acetate as its main ingredient and having the boilingpoint of about 180° C., was applied by the spinner such that its filmthickness at the reflection part became 0.5 μm. Then, a time periodbefore the color resist is dried was set to 7 minutes, and the coloredlayers 3R, 3G, and 3B were formed in succession (FIG. 10E). At thistime, the film thickness of each of the colored layers at thetransmission part was 0.8 μm. In a similar manner as in Example 1, byusing the thus manufactured color filter substrate, thesemi-transmissive type color liquid crystal display device wasmanufactured.

The thus structured semi-transmissive type color liquid crystal displaydevice and the conventional semi-transmissive type color liquid crystaldisplay device were compared for evaluation, and the results are shownin Table 2. For the conventional semi-transmissive type color liquidcrystal display device, two display devices were prepared in which themetallic reflective film 11 each had the thickness of 0.1 μm, and thefilm thickness of the color filters at both the reflection part and thetransmission part was 0.5 μm (Conventional Example 3) or 0.8 μm(Conventional Example 4), respectively.

[Table 2] Comparison in color reproducibility and reflection brightnessbetween semi-transmissive color liquid crystal display device of thepresent invention and conventional semi.-transmissive color liquidcrystal display device (2) Conventional Conventional Example 2 Example 3Example 4 CF Transmission 40% 25% 40% substrate NTSC ratio Reflection52% 52% 63% NTSC ratio Reflection 36% 36% 27% brightness DisplayTransmission 34% 20% 34% device NTSC ratio Reflection 32% 32% 38% NTSCratio Reflection 23% 23% 16% brightness

As is apparent from Table 2, the results show that the colorreproducibility and the reflection brightness at the time of bothtransmission and reflection were extremely well balanced as compared toConventional Examples 3 and 4.

It should be noted here that the passive matrix semi-trasnmissive typecolor liquid crystal display device has been described in theabove-mentioned example, but the case may also be applicable where anactive element such as a TFT is provided to the counter substrate 8 orthe color filter substrate 6. Another metal or its alloy other than thealuminum alloy and the silver alloy may also be applicable.

1.-18. (canceled)
 19. A color liquid crystal display device, comprising:a color filter substrate having a metallic reflective film, coloredlayers, and a transparent electrode formed on a transparent substrate; acounter substrate having an opposite electrode that is opposite to thetransparent electrode and constitutes a display pixel element with thetransparent electrode; and a liquid crystal layer disposed between thecolor filter substrate and the counter substrate; wherein the metallicreflective film is formed on a part of an area of the display pixelelement; and the colored layers are integrally formed on the metallicreflective film and an area where the metallic reflective film is notprovided in the display pixel element.
 20. A color liquid crystaldisplay device according to claim 19; wherein a light shielding film isformed between the colored layers.
 21. A color liquid crystal displaydevice according to claim 20; wherein the light shielding film isprovided on the metallic reflective film.
 22. A color liquid crystaldisplay device according to claim 20; wherein the light shielding filmis formed on an area of the transparent substrate where the metallicreflective film is not formed.
 23. A color liquid crystal display deviceaccording to claim 19; wherein the metallic reflective film has athickness of 0.2 μm or more.
 24. A method of manufacturing a colorliquid crystal display device in which a transparent electrode and anopposite electrode sandwich therebetween a liquid crystal layer toconstitute a display pixel element, comprising the steps of:establishing a reflection part and a transmission part by forming ametallic reflective film on a part of an area of a transparent substratewhere the display pixel element is to be constituted; forming coloredlayers at the reflection part and the transmission part at the sametime; forming a color filter substrate by repeatedly performing thecolored layer formation for each color; forming the transparentelectrode having a desired pattern on the color filter substrate;forming the opposite electrode having a desired pattern on a countersubstrate; arranging the color filter substrate and the countersubstrate such that the transparent electrode and the opposite electrodeare opposed to each other; and forming the liquid crystal layer in aspace between the transparent electrode and the opposite electrode. 25.A method of manufacturing a color liquid crystal display deviceaccording to claim 24; further comprising the step of forming a lightshielding film on a part of the metallic reflective film beforeformation of the colored layers.
 26. A method of manufacturing a colorliquid crystal display device according to claim 24; further comprisingthe step of forming a light shielding film on a part of an area of thetransparent substrate where the metallic reflective film is not formedbefore the colored layer formation.
 27. A method of manufacturing acolor liquid crystal display device according to claim 25; wherein eachof the colored layers is formed by supplying a liquid color resist in apredetermiend area surrounded by the light shielding film.
 28. A methodof manufacturing a color liquid crystal display device according toclaim 27; wherein after the supply of the liquid color resist, theresist is left to stand in a liquid state for 1 minute or longer beforebeing dried.
 29. A method of manufacturing a color liquid crystaldisplay device according to claim 24; wherein the metallic reflectivefilm has a thickness of 0.2 μm or more.
 30. a method of manufacturing acolor liquid crystal display device according to claim 29; wherein thethickness of the metallic reflective film is in a range from 0.4 μm to0.6 μm.
 31. A method of manufacturing a color liquid crystal displaydevice according to claim 29; wherein a thickness of the colored layersat the reflection part is in a range from 0.4 μm to 0.8 μm.
 32. A methodof manufacturing a color filter substrate, comprising the steps of:establishing a reflection part and a transmission part by forming ametallic reflective film on a part of a transparent substrate; formingcolored layers at the reflection part and the transmission part at thesame time; and forming a color filter by repeatedly performing thecolored layer formation for each color.
 33. A method of manufacturing acolor filter substrate according to claim 32; wherein a thickness of thecolored layers at the reflection part is 0.2 μm or more.
 34. A method ofmanufacturing a color filter substrate according to claim 33; whereinduring the colored layer formation, the colored layer on the metallicreflective film is formed to have a thickness in a range from 0.4 μm to0.9 μm, and at the same time the colored layer at the transmission partis formed to have a thickness in a range from 0.55 μm to 1.0 μm.